Kit Weathers and I have made a new video to enable you to sample the pudding of the STS( Successor To Sonics ) canal preparation device without actually buying one.

I wanted to see really how fast I could do a bunch of preparations.

So we set up a close up video camera in the 'Magic Endo Bus' and video taped the preparation of several teeth.

The verdict is up to you but I can tell you that IT WAS FAST.

As one of the attendees told me yesterday in Lynchburg, VA...'It really guts out a canal'.

But along the way we found out something else.

That it is also SAFE.

The reason is part of the STS system which moves the file in Linear Oscillation only about 0.8 mm at a rate of 500 strokes per second(Actually 250 up and 250 down).

I have told many of you in the "Automated Endo" class that there are two ways to break a Fine-Cut file.

You can twist it off or you can buckle it, get it stuck and pull on it.

Since the STS does not turn the file it cannot break it that way.

And since to buckle a file you have to push it beyond bowing it, which takes about 3mm, the STS does not push it that far.

Ergo, no breakage.

In the video, which is available on loan for a $10 deposit refundable toward the purchase of the STS, you can see for yourself some of the technical aspects of STS preparation.

Although it is still a good idea to take the course or to attend one of the AERG study group meetings listed on the back page, you can also buy the STS after seeing the video.

The total cost of the STS system including the Fine-Cut adapter is about $400.00.

There are some conditions, however.

Since the main part of the device is an electice tooth brush, once it is in your hands, I cannot take it back because the California Good Manufacturing Practices Act prevents me from selling it again. ( You surely wouldn't want to buy a used one would you? )

Another reason you might want to take a hands on training session with it is to cover yourself medico-legally although if you have been doing circumferential filing I see no radical departure from you existing technique.

As we get feedback from the users I will pass on the technique tips via this newsletter.

In the Fine Cut System, the flutes get farther apart as you move from tip to shank of the file and as you go from smaller to larger files.

When the inter- flute distance exceeds the up-and-down oscillatory motion of the STS, the flutes don't move far enought to do any cutting.

In order to get the file into the canal easily, turn on the STS first, then holding the STS in a pencil grip, slide your fourth finger foreward to stabilize the file until the tip of the file is in the canal.

Use a #25 or a #30 as an orifice opener as soon as you make your access cavity.

Simply hold the STS with the tip of the file about 3mm into the orifice and circumferentially file.

This gives you better access for your probing files.

If when you do this you can go further, do so.

You may find that you have reached very close to the apex in which case the prep is practically done.

Turn the STS on before you insert the file, holding the file steady with a finger while introducing it into the canal.

When doing curved canals, precurve the file and test it for passive fit before inserting it into the STS.

This is important to avoid zipping and stripping.

Although it is now possible to actually prepare a canal to any size using a small file, it is difficult to avoid creating an amoeba shaped canal by deepening existing vertical grooves.

Going through the sized to 30 can eliminate this problem.

Crown-down preps are very easy.

It is also easy to control the depth since your hand is held steady and thus you can go closer to the apex with safety.

Some dentists are actually using it to prepare the apex as well.

In multiply curved canals, ( read that lower first molars ), a variation of the step back technique can be used, especially if you are using the Milton Syringe to fill.

Probe to the apex with a #15 hand file.

Set a rubber stop on an STS #15.

Insert the file to apical length with the STS running.

Once you reach the apex and begin moving in a circular motion, slowly withdraw the file.

Do this two or three times with the #15.

Then use a #20,inserting with the STS on until the file begins to bind near the apex, slowly withdraw while circumferentially filing as before.

Repeat with the #25 and #30.

This will give you a step back prep with no ledges,or aneurisms.

If the file gets stuck in a canal, simply pull it out and be careful to stay further away from the apex.

Getting a file stuck is of no consequence, as the handpiece simply moves up and down.

If a canal where the file is not precurved and the canal is larger than the file, the file will actually pull itself in until it gets stuck...if you let it.

This same phenomenon happens when using sonics with circumferential filing because the filehas a negative rake on the way in and positive on the way out.

Each in stroke moves the file further in, and you hand tends to follow it in.

DON'T.

Whatever you can do with circumferential filing you can do with the STS, only faster.

That includes zipping the apex if you go past the apex.

That also includes creating an aneurism( a bulge in the outside of the curve short of actual stripping) in the canal if you force a straight file around a curve.

Again,DON'T.

I have not yet broken a file with the STS.

The amount of up and down motion is insufficient to buckle the file.

And since it doesn't turn, it cannot twist off.

Hold the STS handpiece close as close to the tip as you would an air rotor handpiece.

It is easier to handle.

Be sure to use plenty of irrigation.

If it cuts 25 to 50 times as fast as sonics, it also generates fifty times the debris.

Failure to irrigate can pack debris pretty hard and pretty fast.

Store the STS in the charger.

Then it's ready at any time.

Remove the file holder adapter for sterilization by turning the lock nut CLOCKWISE looking at the end of the adapter.

The adapter should then be removed turning with finger pressure only.

Remove the lock nut and sterilize it too.

Put a plastic bag over the STS, puncture the bag with the threaded end of the STS and put the lock nut back on until only about 1/8 inch of threads are visible, then put the adapter back on until it touches the lock nut.

Then adjust the angle of the water port on the adapter until it is at right angles to the on/off button on the STS handle.

Turn the lock nut counter-clockwise to lock the adapter back on.

If you want the STS to have a more vigorous motion, when you put the adapter back on, simply don't screw it down as close to the STS handle.